1. Field of the Invention
The present invention relates to a drive control device. More specifically, it relates to a drive control device to control current applied to a motor based on signals from an encoder for detecting the rotation speed of the motor.
2. Description of Related Art
Conventionally, a drive control device to control the driving state of a motor has been well known. (For example, a document: JP-A-2004-5218)
Such a drive control device includes, for example, a motor to be controlled, an encoder to detect the rotation speed of the motor and output a condition signal, and a drive controller to control current applied to the motor to achieve a desired rotation speed of the motor based on the condition signal from the encoder.
Such a drive control device may be provided with a function to detect and inform malfunction of each component of the device in a form of alarm. For example, a function to detect and inform that the rotation speed of the motor detected by the encoder exceeds the permissible rotation speed of the motor in a form of alarm can be provided. Defects of the motor can be prevented by such a drive control device.
Since a variety of malfunctions of each component of the drive control device can be assumed, an alarm code for indicating the cause of an alarm (i.e. the detail of a malfunction) is generated and sent together with the alarm when the alarm is sent. This feature allows specifying the cause of the alarm and dealing with the alarm with ease.
However, such a conventional drive control device required a costly display unit such as a seven-segment display in order to distinguishably display different alarm codes corresponding to various causes of alarms. The drive control device may be provided with external equipments that read internal information of the drive control device and display alarm codes upon occurrence of malfunctions instead of being provided with the display unit, however, it is disadvantageous in its workability since it requires external equipments to be connected.